Broadband data and video services, on which our society and economy have grown to depend, have heretofore generally not been readily available to users on board mobile platforms such as aircraft, ships, trains, automobiles, etc. While the technology exists to deliver such services to all forms of mobile platforms, past solutions have been generally quite expensive, low data rate and/or available to only very limited markets of government/military users and some high-end maritime markets (i.e., cruise ships).
At present, a wide variety of broadcast television (TV) services are available to terrestrial users via satellite links. Such services include commercial Direct Broadcast Satellite (DBS) services (such as DirecTV® and EchoStar®) and custom video, such as rebroadcast video, over private Fixed Satellite Services (FSS) or Broadcast Satellite Services (BSS) satellites. The data services which can be provided via satellite link include all conventional Internet services (e.g., email, web browsing, NetMeeting, etc.), as well as virtual private networks (VPNs) for corporate and government customers.
Previously developed systems which have attempted to provide Internet services between a mobile platform and one or more ground stations have encountered significant difficulties in maintaining the communications link between the mobile platform and a ground based station as the mobile platform leaves one coverage region and enters a second coverage region. In such instances, where the mobile platform is required to transition from communicating with a first ground based RF transceiver located within a first coverage region to communicating with a second ground based RF transceiver located within a second coverage region, coordinating the hand-off of the communication link from the first ground station to the second ground station presents a problem. The first ground station needs to be apprised when the mobile platform is about to leave its coverage region, and with sufficient advance notice that the first and second transceivers associated with the two ground stations can coordinate transferring the communications link with the mobile platform. More specifically, the two ground stations need to communicate with one another and with the mobile platform so that the mobile platform can be instructed to relinquish its communications link with the first ground based station prior to establishing a communications link with the second ground based station.
It is also important for both of the ground based transceivers to be apprised when the hand-off is complete. When the mobile platform involved is an aircraft moving at a high rate of speed, this problem can be exacerbated. Depending upon the distance or area of overlap between the two coverage regions, only a very limited amount of time may be available to establish a new communications link as the aircraft leaves the first coverage region and enters the second coverage region.
In view of the foregoing, it is a principal object of the present invention to provide a system and method for coordinating the break of an existing return communications link between a mobile platform and a first ground based transceiver located within a first coverage region, and establishing a new communications link between the mobile platform and a second ground based transceiver located within a second coverage region, where the mobile platform is communicating with the ground based transceivers via satellite transponders orbiting above each of the first and second coverage regions.
It is another object of the present invention that such a hand-off of the communications link between a mobile platform and a pair of ground-based transceivers is to be accomplished within a relatively short period of time such as, for example, less than one minute, as the mobile platform enters an area of overlap between the two coverage regions.
It is yet another object of the present invention that such a hand-off of the communications link from a first ground based transceiver to a second ground based transceiver can be accomplished with communications between each of the ground based transceivers occurring to positively inform the first ground based transceiver that a new communications link has been established with the second ground based transceiver.